Atrial fibrillation is a complex and seemingly chaotic arrhythmia that has been described as an emerging epidemic. The empirically validated approaches of electrically isolating the pulmonary veins (and antrum) from the left atrium with ablation have demonstrated only moderate success rates, with paroxysmal atrial fibrillation patients responding better than those with persistent atrial fibrillation. Success rates of these procedures can be improved by adding additional ablation or surgical lesions in the atria. Strategies moving beyond the current empirical approaches are needed to improve treatment. Although intracardiac electrical recordings from catheters are routinely obtained during ablation procedures, use of these recordings by clinicians to guide ablation has been limited due to the lack of understanding of the complex nature of these electrograms, specifically how to use these electrograms to identify sites that are critical for the maintenance and perpetuation of these arrhythmias.